"The best research for sports conditioning today says that intensity is key," he explains. "It's not necessary to spend long hours in the gym or hitting the pavement or the track. It's how much energy you can put into short bursts."

Hatmaker offers a half-dozen exercises from his latest book, "Boxer's Book of Conditioning & Drilling" (Tracks Publishing), that will get a person into fighting trim. And if you're in shape to box, you're in shape, period.

"Boxing is as grueling as anything can be. It's just exhausting, soul-sucking," he says. "We see people who run marathons, and they can't last three minutes in the ring. And that's not even because of the hitting. It is just that exhausting."

Hatmaker says to approach the eight exercises as a circuit (if a circuit of eight is too much, pick at least four):

Do as many repetitions as you can in one minute, for each exercise.

No rest in between.

After completing the eight exercises, rest for one minute.

Then do the circuit again.

Two circuits, just 17 minutes a day, will do it.

Dive bombers (for arms and core)

All fours on the floor, place your feet two shoulder-widths apart. Arch your hips as high as you can, as you might in downward dog in yoga. Sweep your chest down and between your arms until your hips brush the floor. Reverse the motion.

Mountain climbers (for arms and core)

Get into push-up position, and quickly bring your right knee up to your right elbow, then back. Repeat with the left knee to the left elbow. That's one.

Burpees/squat thrusts (total workout)

Stand at attention. Drop to a squatting position, place both hands on the floor in from of you, and thrust both legs out backward, resulting in a push-up position. Do one push-up, quickly bring your legs back to return to the squatting position, then leap 8 to 12 inches into the air, clapping your hands overhead.

Maximum punch rate circuit (for punching skills)

Set a timer for one minute and throw as many punches as you can in that minute, counting each right and left combination as one repetition. Rest one minute, then repeat, trying to hold as close as possible to your original punch count in each successive round. Repeat for six one-minute rounds total.

Float and sting circuit (for timing and agility)

Set a timer for three minutes. Hit any variation of footwork you desire as you stay on the move, flicking punches. The focus here is on movement — shuffle, side-step, slip, bob and weave to your heart's content. Rest for one minute. Perform for a total of three three-minute rounds.